1. Field of the Invention
The present invention relates generally to systems and methods for positioning and maintaining a region of soft tissue in a desired orientation to facilitate imaging, and the performance of a procedure in the soft tissue. More specifically, systems and methods for the orientation of soft tissue such as breast tissue for enhanced accuracy of imaging and/or procedures such as a biopsy or excision are disclosed.
2. Description of Related Art
Before a lesion within breast tissue of a living subject can be properly targeted and treated, the breast tissue is often imaged in order to locate and delineate the lesion. Once the location of the lesion is determined, it is often necessary to insert an invasive device such as a guide wire into the breast tissue to target the lesion. Ideally, the tip of the guide wire is placed near the lesion within the breast tissue. The guide wire helps direct the surgeon to the lesion during an operative procedure.
There are several disadvantages in such a procedure using the guide wire. For example, using a guide wire is a cumbersome and time consuming process. The pre-operative guide wire placement is typically performed in a separate department from the operative procedure, often adding hours of time. In addition, the guide wire can move within the breast before the operative procedure is conducted. Further, only a rough estimate of the actual location of the tip of the guide wire within the breast tissue can be made prior to making the skin incision which often leads to inaccurate or excessive tissue excision.
An imaging process at the time of the operative procedure would eliminate the need for pre-operative guide wire placement and would allow more accurate targeting of the lesion.
From the start of the imaging and localization process to locate the lesion to the completion of the procedure to address the lesion, the breast tissue should be optimally positioned and maintained in the desired orientation during the entire process. For example, if the breast tissue moves after localization of the lesion by imaging and before the procedure, the region of the procedure may not be that of the lesion. Thus, minimally invasive devices and procedures on the breast that require imaging often require breast immobilization.
Conventional breast immobilization devices have resulted from the techniques of mammography in which the breast is compressed and held immobile between two rigid and parallel plates. After using mammography to localize the lesion within the breast, the breast remains compressed and immobilized between the two compression plates to provide a platform from which to conduct the diagnostic procedure. Thus the breast stays in compression during the entire localization and biopsy procedures. However, there are a number of disadvantages with the use of parallel compression plates. For example, such a breast compression device and associated procedures are uncomfortable, awkward, and painful for the patient. In particular, the patient is often required to assume an uncomfortable position to fit the breast between the plates and the degree of compression necessary to properly stabilize the breast in this manner is great. In addition, compression distorts the internal structures of the breast, jeopardizing the accuracy and effectiveness of the procedure. Conventional breast immobilization devices also do not orient the tissue in a manner conducive to providing an optimal site for a skin incision to perform the procedure.
Sonographic localization of the lesion is another method used to target lesions in the breast tissue for sampling or excision. For example, a physician may use ultrasound to guide a fine needle aspiration, core biopsy, or vacuum assisted core biopsy. In such a procedure, rather than compressing the breast, an ultrasound transducer is typically used to image the breast to locate the lesion. In a biopsy guided by ultrasound, the physician needs to simultaneously stabilize the breast, hold the ultrasound transducer, and perform the biopsy accurately enough to obtain tissue from the lesion while maintaining the needle within the imaging plane of the ultrasound transducer. It is difficult for the physician to have an assistant help perform the procedure because the ultrasound transducer and biopsy device need to be in precise alignment in order for the biopsy device to be visualized on the ultrasound monitor. Furthermore, the breast moves in response to even slight pressure or patient movement due to, for example, coughing or even the patient's heartbeat. Such movement may make imaging and targeting of a lesion during a procedure in the breast difficult and may also cause the biopsy device and ultrasound transducer to misalign.
Nonetheless, such sonographic imaging and procedures on an uncompressed breast would generally be more comfortable for the patient, may allow more entry site choices for the surgical device, and may provide for excising of tissue from the breast in its natural state. One example of an ultrasound examination of the breast is described in U.S. Pat. No. 5,709,206 to Teboul, the entirety of which is incorporated by reference herein. In particular, Teboul describes utilizing ultrasound examination of the internal breast anatomy to study the lesion and its relation to the duct in which it developed. By using axial ductal ultrasound scanning, identification and characterization of the lesion, position within the lobe, and the possibility of spread within the duct or ducts and/or the identification other lesions within the affected lobe (e.g. multifocal cancer) can be delineated prior to a biopsy or treatment procedure. In order to facilitate identification and characterization of the ducts, the ducts should ideally be in a straight alignment with the length of the ultrasound transducer such that as much of the length of the duct as possible is within the imaging plane of the transducer. The ducts can be straightened manually by applying slight pressure using a transducer with a length of at least 6 cm. Maintaining the ducts as straight as possible during an invasive procedure would facilitate the accuracy and ease of the procedure.
Accordingly, there is a need for a system and method for orienting the soft tissue in an area of the breast or other soft tissue and for maintaining or immobilizing the soft tissue in the desired orientation that enhance accuracy of imaging and/or procedures. Ideally, the system and method allow imaging of a procedure as it is being performed for improved effectiveness and accuracy of the procedure.